Method of making stay-bolt taps



Sept. 16 1924- G. M. BRUBAKER, JR

METHOD OF MAKING STAY BOLT TAPS Filed Jan. 24 1924 EMF? Patent Sept. 16, 1924.

STATES 1,508,595 PATENT OFFICE.

GORDON MARK BRUBAKER, JR, 015 MILLERSBURG, PENNSYLVANIA, ASSIGNOR TO W. L. BRUBAKER & BROS. COMPANY, OF MILLEBSBURG, PENNSYLVANIA.

METHOD OF MAKING STAY-BOLT TAPS.

Application filed. Januar'y 24, 1924. Serial No. 688,283.

To all whom it may concern:

Be it known that I, GORDON MARK BRU- BAKER, Jr., a citizen of the United States, residin at Millersburg, in the county of Dauphin and State of Pennsylvania, have invented new and useful Improvements in Methods of Making Stay-Bolt Taps, of which the following is a specification.

My invention relates to a method of making staybolt taps of the general type 'disclosed in In prior Patent No. 1,434,870, dated November 7 1922, and of the particular typedisclosed in my copending application filed Jan. 24, 1924, Serial No. 688,232, both relating to a staybolt tap having a forward reaming portion and a rear threading portion, said threading portion being composed of tapered cutting threads and uniform fin ishing threads, and said tap'bein provided with spiral clearance grooves or utes forming spiral ribs, the ribbed portions of the reamer part bein rovided with the reamer cutting edges an t e ribbed portions of the tap art with the aforementioned threads. In t e patented structure referred to, the grooves or flutes and the ribs of the reaming and tap portionsextend on continuous spiral curves in the same direction, a con struction which has been found to be somewhat objectionable under certain conditions in simultaneously reaming an inside boiler sheet and ta ping an outside boiler sheet, ow-

ing to the ow of the chips formed by both cutters in the same direction along the flutes of the tooL' In the construction shown inv my copending application, Serial No. 688,232, this objection is overcome by having the flutes and ribs of the reaming and tap portions extending spirally in reverse directions as therein fully described.

The object of the present invention is to provide a simple, convenient and inexpensive method of making a staybolt tap of the type disclosed in my said copending application Serial No. 688,232.

In the accompanying drawing,-

Figure 1 is a s1de elevation of the tap.

as it appears. when partly completed and prior to the finishing steps.

Figure 2 is a similar view of a ortion of the incomplete tap as shown in Figure 1, on an enlarged scale. 5

Figure 3 1s a cross-section taken substan- I tially on line 3 23 of Figure 2.

tially on the line 6-6 of Figure 5.

Figure 7 is a longitudinal section taken substantially on line 77 of Figure 6.

Figure 8 is a view of the completed tap with the threads'thereof illustrated diagrammatically.

The completed staybolt tap embodyin my invention, shown fully in Figure 8' an fragmentarily in Figures 5 to 7, inclusive, comprises a shank 1 provided with the forward reamer portion 2, the intermediate tap portion 3, and the rear tang portion 4, said tang portion having the usual angular end or head 5 by meansof which it may be turned. As shown, the tap portion 3 has two threaded surfaces, to Wit, a forward threadingcutting surface extending between the points 6 and 7 and composed of tapered threads 8, and a rear threaded finishing surfac extending between the points 7 and 9 and composed of uniform threads 10, said threading surfaces intersecting at the point 7. Also as shown, the reamer portion 2 extends from the extreme forward end of the tool to a point adjacent the point 6, and

the shank tapers from the point 7 to such extreme forward end of the tool.

The shank is formed with longitudinal flutes or grooves 11-11, producing the spiral ribs 1212', on which ribs 12 the threads 8 and 10 are formed. Each groove 11 of the threading portion is continuous with a groove 11 of the reaming portion, and each rib 12 of the threading portion is also continuous with a rib 12' of the reaming portion. The grooves 11 11' and ribs 12-12 .thus extend the full distance from the forward end of the tool to the point of intersection 9 between the working portions of the shank and' the tang 4, the grooves providing clearance channels for tlie reception and discharge of the chips from both the reamin and threading cutters, and the edges 13 o the ribs 12' forming the acting reaming cutters. In the use of the tool, the reamer portion is em loyed to ream out the hole which is to, be t readed,=which operawith each other throughout the length of the working portions of the tool, but the grooves 11 and ribs 12 extend spirally in one direction, while the grooves 11' and ribs 12 extend spirally in the reverse direction, in

accordance with the structure set forth in .my aforesaid copending application Serial No. 688,232. In ractice the grooves and ribs of the threa ing portion may be left hand grooves and ribs,-while the grooves and ribs of the reaming portion may be right hand grooves and ribs, or the reverse may be the case. p

The present invention is directed to a novel manner of making a staybolt tap of this construction, whereby an economical and practical mode of manufacture is furnished. In this method of manufacture the tap is blanked out from abar of steel and then headed and threaded. After the tap is threaded, the thread is machined, and then the tap is milled with a right hand spiral on the reamer part, thus producing t e grooves 11' and ribs 12, after which the tap is milled with a left hand spiral along the threaded or tap portion proper, thus producing the grooves 11 and ribs 12. This millin is carried out insuch manner as to cause 5K} grooves or flutes of the reaming and tap portions to intersect or merge together at the point of joinder of the reamingportion wit the threading portion. At thls point in the reverse spiral milling cuts, where each groove 11 and continuing groove 11' intersect each other, an upstanding ridge or fin 14 is left at the marginal points of out. These ridges are then removed in any suitable manner, as by grinding, in order to make the grooves of full depth at their points of intersection, thus makmg each continuous groove, formed of a oove 11 and comppnion groove 11', of li e width and dept omt an easy curve for the flow of the chips rom one roove portion to the other. In other wor s, this grinding operation makes the hook and rake the same throughout the entire length of the flute of the ta Finally, the tapered lead-portions 15 an 16 may be groundon the reaming and ta 2 and 3, and the tap given. suc ishing grindin s as may be necessary, then hardened an otherwise treated so as to put it in as desirable a shape as required for shipment as a market product. I

The method of manufacture above described adapts a combined reamer and ta of the structure set forth to be produce without manufacturing difliculties, enabling throughout, and providing at this' ortions a su erior article to be made in an easy, rapi and convenient manner.

By'this method there is produced a staybolt tap having a reaming portion extending spirally in one direction and a tap portion extending spirally in the reverse direction, whereby the chips formed by the reamer are caused to flow along the reamer fully described my invention,

. reamer and tap having reaming and threading portions arranged one in advance of the other, which consists in threading a suitable blank, milling fiutes extending spirally in one direction along-the tap portion of the blank, milling continuing utes extending spirally in the reverse dlrection along the reaming portion of the blank, grinding out the ridges between the intersecting ends of the flutes, and then suitably finishing the surfaces of the tool.

2. The method of making a combined reamer and tap having reaming and threadin portions. arranged one in advance of the ot or, which consists in-formin threads on the threading portion, milling utes extending spirally in reverse directions along the reaming and threading portions, removing the ridges left by the milling tool at the pointsof intersection of the flutes, and then suitabl finishing the surface of the tool.

3. The method of making a combined reamer and tap having reaming and threadin portions arranged one in advance of the ot er, which consists in threading a suitable blank, milling flutes extending spirally in opposite directions along the, reaming and threading ortions of the blank, removing the ridges ieft by the millin tool between the intersecting ends of the utes, grinding leads on the reamer and tap portions, reducing down the blank to a taperfrom a point between the ends of its threaded rtion'continuously -'to the extremity 0 its reaming port-ion, hardening the blank, and then suitably finishing the same. 1

4. The method of 'making a combined reamer and tap havin rear reaming and front tap ortions o the character described, whlch consists in cutting threads.

full tap portion of the tool, milling flutes extending spiral] in one direction along the portion of the..b ank which isto constitute the reaming portion of the tool, milling continuin flutes extending spirally in the reverse irection along the tap portion, grinding out the ridges left between the intersecting ends of the, flutes of said portions so as to make the hook and rake of the connected flutes uniform throughout their length, and then reducing down the blank so as to taper the tool longitudinally from a point intermediate of the length of the. 0 tap portion continuously to the forward extremity of the reaming ortion.

In testimony whereof I a my signature. GORDON MARK BRUBAKER, JR. 

